Method of forming textured yarn



United States Patent 3,377,794 METHDD 6F FQRMING TEXTURED YARN Howard R.Walker, Evans, Ga", assignor to Deering Milliken Research Corporation,Spartanburg, S.C., a corporation of Delaware No Drawing. Filed Mar. 30,1964, Ser. No. 355,921 6 Claims. ((Il. 57-157) This invention relates tothe art of producing textured yarns and fabrics. In particular, itrelates to novel composite yarns, to fabrics produced from such yarns,and to the method of producing these textured yarns.

The art is now replete with methods for forming textured syntheticyarns, and fabrics therefrom, which have many of the qualities of thenatural apparel yarns and fabrics. The early problems encountered inimparting to synthetic fibers and yarns the appearance, flexibility,absorbency, hand and other fine qualities possessed by the naturalfibers and yarns are well known. In particular, and even yet of acuteinterest, are methods for imparting to synthetic fibers and yarns thespecial qualities of bulk and elasticity.

Present methods for texturizing yarns serve their purpose admirably,though in varying degrees. Such methods require, inter alia, however,relatively expensive and complex apparatus for the production of suchyarns. Textured yarns are thus manufactured by various core spinningtechniques and especially by the heat treatment of thermoplastic yarnsby such methods as gear-crimping, stuifer box-crimping, falsetwist-crimping, edge-crimping and the like. In these methods a syntheticthermoplastic yarn is deformed or placed in some desired configurationand then set by softening with heat and then cooling to effect settingin the deformed condition. The configuration in which the yarn is setmay even be removed. Even though set thermoplastic yarn is not permittedto remain in the condition of its deformity, it nevertheless, however,possesses an elastic memory or potency to return to its original heatset condition. Because of such memory, the yarn takes on a texturedappearance and generally possesses elasticity. Thus, upon application ofa deforming force the yarn will be extended and, upon removal of suchforce, the yarn will return to its relaxed condition.

The yarn also possesses bulk provided by its crimped condition orirregular extension into space, as caused by curls and kinks resultantfrom such treatment. Bulk and elasticity are present in such texturedyarns in varying degrees.

While such methods of producing textured yarns, especially those havinggood bulk and elasticity, have been very successful there isnevertheless an acute need to provide simpler methods of producing suchtextured yarns.

It is in fact, the primary objective of the present invention to fulfillthis need and to provide the art with a relatively simple method for theproduction of such textured yarns. Another object is the provision ofnovel composite yarns, or fabrics composed of such yarns, which can beheat treated to provide textured yarns and fabrics.

These and other objects are achieved in accordance with the inventionwhich contemplates the formation of a composite yarn structure bytwisting or plying together a plurality of yarns, including a firstthermoplastic yarn and a second heat shrinkable yarn. By applying heatto this composite yarn the heat shrinkable yarn contracts or shrinks tocause distortion of said first thermoplastic yarn into the configurationof a series of randomly located loops and coils. Heating to thesoftening temperature of the said first thermoplastic yarn sets theconfiguration of loops and coils into said first thermoplastic yarn.Separation of the first thermoplastic yarn from the composite yarnprovides a textured yarn.

The heat shrinkable or second yarn is also preferably a thermoplasticyarn having a flow temperature less than that of the first thermoplasticyarn, and also less than the softening temperature of the firstthermoplastic yarn. By providing a composite yarn wherein the flowtemperature of the heat shrinkable or second yarn member is lesser thanthat of the first yarn or thermoplastic yarn member to be heat set, andbelow its softening temperature, the composite yarn can be heated toeffect contraction of the shrinkable yarn. The temperature of the yarncan then be elevated to the softening temperature of the said firstthermoplastic yar-n to effect its heat setting. In heating such yarncomposite ultimately to the softening temperature of the firstthermoplastic yarn in this manner the second thermoplastic yarn meltsand is thus separated from the yarn composite. In this manner, thecomponent parts of the composite yarn are separated quite convenientlyand require no untwisting or other physical or chemical separation ofthese members. In such embodiment, preferably, the fiow temperature ofthe second heat shrinkable thermoplastic yarn ranges from about 18 toabout 45 Fahrenheit degrees less than the softening temperature of saidfirst thermoplastic yarn. It is apparent that if the heat shrinkableyarn volatilizes or heat decomposes below the softening temperature ofthe first thermoplastic yarn that essentially the same result will beachieved. Moreover, it is apparent that fabrics of such composite yarnscan be heat treated in similar fashion to provide textured fabrics.

A feature of the invention is that the size of the loops and coilsformed within the first thermoplastic yarn can be controlled by thequantum of twist applied to a composite yarn. Thus, a high quantum oftwisting will reduce the size of the coils or loops, but will increasethe number thereof per unit of linear measurement. Conversely, a lesserquantum of applied twist will increase coil and loop size, and thelesser will be the number of coils or loops per linear unit ofmeasurement. Preferably, a twict ranging from about one-half to aboutthirty turns to the inch, and more preferably from about five to aboutten turns to the inch, is provided for optimum results. Numerous simplemethods of twisting or plying yarns together are well known to the art,and quite obviously the twisting can even be done by hand.

The following non-limiting examples are illustrative of preferredembodiments of the present invention.

On an Atwood lO-B twister, composite yarns of the following types wereprepared:

A. 1.2/70 denier nylon 66 plied with 14 denier polypropylene five turnsof Z twist to the inch.

B. A second yarn was prepared as in (A) using 2/70 denier nylon and 40denier polypropylene, and

C. A yarn composite was prepared as in (A) using 2/ denier nylon and 14denier polypropylene.

D. A yarn composite was prepared as in (A) using 2/ 140 denier nylon and40 denier polypropylene.

Each of the composite yarns described above were then heated to 300 F.in the dry heat of a circulating oven for a period of fifteen minutes.At this temperature the polypropylene was shrunken, and the nylondistorted into a configuration of loops and coils randomly spaced alongthe length of the composite yarn. The temperature was then raised to 400F. for a period of fifteen minutes which melted the polypropylene whilesimultaneously softening and heat setting the nylon in the aforesaidshrunken configuration. The yarns were then removed from the oven. Theresulting textured yarn was found to possess considerable bulk and hadgood resiliency or elasticity. When the yarns were knitted and woveninto fabrics good stretch properties were imparted to these fabrics.

When composite yarns A, B, C, and D, respectively, are knitted andsubjected to a similar time-temperature a elevation profile as in theforegoing, knitted elastic fabrices of good quality are obtained. Thesame is found to be true of fabrics woven of yarns A, B, C, and D,respectively, which are heat treated in similar fashion.

The key and novel feature of the present invention resides in theformation of a composite structure wherein thermoplastic yarn componentscapable of being set, are twisted or plied together with heat shrinkableyarn members which can be heat contracted to produce deformation of theformer. Moreover, preferably the latter will not only shrink uponapplication of heat but which will also melt, volatilize or decomposebelow the softening temperature of the thermoplastic yarns to be heatset. And, most preferably, the composite yarn is formed of yarns whichwill be shrunken at a first temperature to affect loop configurationwithin thermoplastic yarns to be heat set and, upon further increase intemperature to the softening temperature of the latter the heatshrinkable yarn components will flow and become separated from thecomposite yarn structure.

It is thus apparent that the heat shrinkable yarn members of thecomposite structure first serve as a matrix for shaping by deformationof the thermoplastic yarns to be heat set in the form of loops andcoils. Then upon the heat setting of the latter in the desiredconfiguration the former is thus conveniently removed by the heattreating leaving behind only heat set shaped textured thermoplasticyarns.

The invention therefore contemplates preselection of the yarns of thecomposite yarn structure in accordance with these principles,recognizing that certain species of the thermoplastic yarns can be usedin a given yarn composite as the first thermoplastic yarn or yarns to bedeformed and heat set and yet in another different composite yarn as thesecond or heat shrinkable yarn member of the component. Conversely, thesecond thermoplastic yarn or heat shrinkable yarn of one composite yarnmay serve as the yarn to be heat set but in another composite yarn maybe the heat shrinkable member. The selected yarns, however, differaccording to their physical properties as explained.

In general, the heat shrinkable thermoplastic yarn members utilized inaccordance with this invention are those having a flow temperatureranging from about 200 F. to about 350 F., more preferably from about250 F. to about 350 F. (A.S.T.M. D569-59, procedure A).

Exemplary of such materials are polyethlene, polypropylene, preferablyhigh density polypropylene, polyvinyl alcohol, polyvinyl acetate,cellulose acetate, other thermoplastic derivatives of cellulose,polyvinyl butyrates, the lower melting nylons and the like.

The synthetic thermoplastic yarns which can be deformed and heat set inaccordance with this invention are those widely disclosed and acclaimedin the technical and patent art, especially in the cramping art, i.e.,stufferboxcrimping, edge-crimping, false twisting and gear-crimping.(See, e.g., Shirley Institute Pamphlet No. 81, A Survey of theLiterature and Patents Relating to Bulked Continuous Filament Yarns, byE. A. Hutton and W. J. Morris.) In general, however, such yarns arethose having a softening temperature ranging from about 250 F. to about450 F. and preferably from about 350 F. to about 450 F. Exemplary ofsuch yarns or such artificial filaments are regenerated celluloseproduced from viscose, nitrocellulose, cuprammonium acetate, celluloseesters, such as cellulose acetate, cellulose propionate, celluloseacetate butyrate; cellulose ethers, such as ethyl cellulose and benzylcellulose; nylons, such as the polyamides; proteinous fibers such asthose from casein; resin fibers such as the vinyl polymers, e.g.,polyvinyl chloride, polyvinylidene chloride, copolymers of vinylchloride and vinyl acetate, copolymers of vinyl chloride andacrylonitrile, polyethylene; resins from polyacrylic derivatives, suchas polyacrylonitrile; and the like.

Yarns are also selected on the basis of providing the desired resultsafter only a few minutes of heating depending in part upon thetemperature employed, the relative flow temperatures of the compositemembers and the efficiency of the heating system employed. Numerousmethods of heating these composite yarns are available and essentiallyany method can be used which is compatible with the preservation of thefinal yarn product and with the method steps to be achieved. The heatemployed can be of Wet or dry type, e.g., wet or dry steam, gas such asair and the like. Radiant heat can be used or heat may be applied to theyarn in the form of a hot contact surface upon which the yarn impinges.A source which will provide uniform heating is preferred. Accordingly,the invention should not be limited except as within the scope of theappended claims.

Having described the invention what is claimed is:

l. A method of forming textured thermoplastic yarns comprising forming acomposite yarn by twisting together a pluarility of yarns including afirst thermoplastic yarn and a second heat shrinkable yarn, and thenapplying heat to said composite yarn to effect contraction of the heatshrinkable yarn thereby causing said first thermoplastic yarn to assumea configuration having a series of randomly disposed loops and coilsalong its length, heating said composite yarn to the softeningtemperature of said first thermoplastic yarn to effect setting of saidfirst thermoplastic yarn in the aforesaid configuration and separationof the first thermoplastic yarn from the yarn composite.

2. The method of claim It wherein the composite yarn is formed of afirst thermoplastic yarn and a second heat shrinkable thermoplasticyarn, said second thermoplastic yarn having a how temperature less thanthe softening temperature of said first thermoplastic yarn.

3. The method ofclaim 2 wherein the second thermoplastic yarn has a flowtemperature ranging from about 18 to about 45 Fahrenheit degrees lessthan the softening temperature of the first thermoplastic yarn.

4. The method of claim 1 wherein the composite yarn is twisted togetherat from about one-half to about thirty turns per inch.

5. A method of forming textured thermoplastic yarns comprising forming acomposite yarn by twisting together a plurality of yarns at from aboutone-half to about thirty turns to the inch, said composite yarnsincluding a first thermoplastic yarn having a softening temperatureranging from about 250 F. to about 450 F. and a second heat shrinkablethermoplastic yarn having a flow temperature ranging from about 200 F.to about 350 F. and at least about 18 to about 45 Fahrenheit degreesless than the softening temperature of the first thermoplastic yarn,applying heat to said composite yarn to effect contraction of the heatshrinkable thermoplastic yarn thereby causing said first thermoplasticyarn to assume a configuration having a series of loops and coilsrandomly disposed along its length, then further heating said compositeyarn to the softening temperature of said first thermoplastic yarn toeffect setting of said first thermoplastic yarn in the aforesaidconfiguration and thereby melting the said heat shrinkable thermoplasticyarn and thus effecting its separation from the said first thermoplasticyarn, and then reducing the temperature.

6. The method of claim 5 wherein the composite yarn structure includes afirst thermoplastic yarn of nylon and a second thermoplastic yarn ofpolypropylene.

References Cited UNITED STATES PATENTS 2,450,948 10/1948 Foster 28-722,575,008 11/1951 Dorgin 57-104 X 2,575,753 11/1951 Foster 57-104 X2,789,340 4/ 1957 Cresswell 28-72 2,911,704 11/1959 Brown 28-723,061,998 11/1962 Bloch 57-140 JOHN PETRAKES, Primary Examiner.

1. A METHOD OF FORMING TEXTURED THERMPLASTIC YARNS COMPRISING FORMING ACOMPOSITE YARN BY TWISTING TOGETHER A PLURALITY OF YARNS INCLUDING AFIRST THERMOPLASTIC YARN AND A SECOND HEAT SHRINKABLE YARN, AND THENAPPLYING HEAT TO SAID COMPOSITE YARN TO EFFECT CONTRACTION OF THE HEATSHRINKABLE YARN THEREBY CAUSING SAID FIRST THERMOPLASTIC YARN TO ASSUMEA CONFIGURATION HAVING A SERIES OF RANDOMLY DISPOSED LOOPS AND COILSALONG ITS LENGTH, HEATING SAID COMPOSITE YARN TO THE SOFTENINGTEMPERATURE OF SAID FIRST THERMOPLASTIC YARN TO EFFECT SETTING OF SAIDFIRST THEREMOPLASTIC YARN IN THE AFORESAID CONFIGURATION AND SEPARATIONOF THE FIRST THERMOPLASTIC YARN FROM THE YARN COMPOSITE.